What is the risk of allowing a pump to operate above its recommended RPM?

Operating a pump above its recommended RPM poses significant risks, primarily due to the phenomenon known as cavitation. When a pump's RPM exceeds its design specifications, it can create conditions where the pressure in the pump drops below the vapor pressure of the liquid being pumped. This results in the formation of vapor bubbles within the liquid.

As these bubbles travel through the pump and reach areas of higher pressure, they collapse violently, which can cause severe damage to the pump components, including the impeller and casing. This cavitation damage can lead to a decrease in efficiency, higher maintenance costs, and potentially complete pump failure.

In contrast, the other options do not align with the risks associated with operating a pump above its recommended RPM. Increased energy efficiency and enhanced pumping capacity would be desirable outcomes, but they are not realistic when exceeding operating limits. Additionally, reduced hydraulic pressure is contrary to what might be expected with increased RPMs, as the expectation would typically be the opposite—an increase in hydraulic pressure until cavitation occurs. Thus, understanding the impacts of exceeding RPM limits is crucial for the longevity and reliability of pump operations.